Development of the batch microcalorimeters has been continued with major emphasis being placed on improvement of sample cells, electronics, temperature regulators and the development of a microprocessor for data processing. Several enzyme reactions are being studied with a view to clinical analysis. Because of the large amounts of enzymes needed for the required sensitivity several of the enzymes are being immobilized on glass beads so that they can be used repeatedly. A fluidic logic flow system has been developed and tested on the stopped-flow microcalorimeter. Both this unit and the syringe drive unit are operating well and the only remaining problem is obtaining rapid, thermoequilibrium of the incoming solutions. The artifact from mixing is less than 1 microcalorie. A new combined pH-thermal titration cell has been constructed and tested. Several improvements are being made and a differential cell is also under construction. A sensitivity of 0.1 milli-degree is now routine in a 2 ml sample.